MINNEAPOLIS, MINN. ? A few years ago, Eric Buenz came across a 17th-century book on herbal medicine.

And he wondered if its ancient folk wisdom could withstand a little scientific scrutiny.

So Buenz, then a graduate student at the Mayo Clinic, and a colleague decided to test a tree extract that the book claimed could cure diarrhea.

What they found was that the potion, made from the nuts of the atun tree, works a lot like an antibiotic, killing various types of bacteria.

And in a report in the British Medical Journal this month, they explain how a 300-year-old text by a Dutch naturalist named Rumphius could help scientists in their search for new and better drugs.

“It was lost traditional knowledge,” Buenz said.

Buenz, 29, traveled to Samoa to collect the nuts and consult with shamans. “And we tested it and it worked.”

Mayo and the scientists have obtained a patent on the medicinal properties of the atun tree nut, in hopes someone might develop it into a drug.

“Our findings,” they wrote in the journal, “show that potential drugs can be identified by searching historical herbal texts.”

In a way it’s not surprising, because many prescription drugs come from natural substances, said Dr. Brent Bauer, one of the co-authors and director of the Mayo Clinic’s complementary and integrative medicine program.

“There’s a reason why they chose the plants they did, why they prepared them the way they did,” he said of traditional healers. “The fact that we can somewhat validate ancient knowledge is cool because a lot of this ancient knowledge is disappearing.”

In this case, the “ancient knowledge” probably would have disappeared if not for the dogged persistence of Georg Everhard Rumphius, a mercenary with the Dutch East India Company, whose story is recounted in the Dec. 23 British Medical Journal article.